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2 Port 3A Universal USB Charger

Mike Taylor
Prodigy 30 points
Other Parts Discussed in Thread: TPS2546, BQ24297

I am designing a 3A 2 port universal USB charger and I am looking at the TPS2546 USB charging port controller and it port power management to help manage the loads if 2 devices are plugged in to charge. I would like to allow either port to charge a device at 2A but once the 2A device is plugged in limit the second port to 1A if a second device is plugged in.


Section 8.3.7 Port Power Management (PPM) on page 22 and Figure 36. Implementing Port Power Management in a System Supporting Two Charging Ports on page 24 of the TPS2546 data sheet shows a configuration that might work for me but it is unclear what I do with the CTL1,CTL2, & CTL3 signals in this case since the figure implies that a controller is present and in a dedicated charger that is not the case.


It looks like CTL1, CTL2, CTL3 set as 0, 1, 1 respectively is the way to go with ILIM_SEL toggling with the STATUS signals but I am unsure. Also, am I limiting the types of devices that I can charge with this setup?

Thank you for any help you can provide.

  • 0
    TI__Guru**** 166826 points
    TPS2546 is used to create one or more USB ports of different current capabilities (SDP-100mA, DCP-1.5A, etc.) that are compliant with the USB BC 1.2 specification. This port then powers a battery charge IC such as bq24297 with D+/D- input pins. The BC1.2 specification defines a protocol for battery chargers to know how much current they can pull from the USB port without crashing the port until the attached device's host processor performs USB enumeration. After enumeration the host should have a better idea of the USB port's actual capabilities and can change the charger's input current limit to match if necessary.
  • 0 in reply to Jeff F
    Prodigy 30 points

    Hi Jeff,

    Thank you for the response but I want to use the TPS2546 on the other end in a universal wall wart charger so I have no Host or controller. I want to use the TPS2546 to do the negotiation with a mobile phone or tablet to set the current capabilities from the chargers point of view.I would also like to use the Port Power Management capability to do adaptive current limiting based on the devices that are plugged in.

    From the TPS2546 data sheet it appears that this is an appropriate use of the part, in Application section 2, Universal Wall-Charging Adapters.

    Maybe this is not the correct forum for this question, please let me know if there might be a better place to post this.

    Mike

  • 0 in reply to Jeff F
    Prodigy 30 points
    Hi Jeff,

    Thank you for the response but I want to use the TPS2546 on the other end in a universal wall wart charger so I have no Host or controller. I want to use the TPS2546 to do the negotiation with a mobile phone or tablet to set the current capabilities from the chargers point of view.I would also like to use the Port Power Management capability to do adaptive current limiting based on the devices that are plugged in.

    From the TPS2546 data sheet it appears that this is an appropriate use of the part, in Application section 2, Universal Wall-Charging Adapters.

    Maybe this is not the correct forum to ask this question, please let me know if there might be a better place to post.

    Mike
  • 0
    TI__Intellectual 1710 points

    You will want to configure the CTL lines for DCP mode since you do not have a host to do USB communications.